<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<title>Document</title>
	<style>
		.outer {
			width: 800px;
		}
		.box {
			width: 200px;
			height: 300px;
			border: 2px solid red;
			margin: 5px;
			float: left;
		}
	</style>
</head>
<body>
	<div class="outer">
		<dvi class="box box1">盒子1</dvi>
		<dvi class="box box2">盒子2</dvi>
		<dvi class="box box3">盒子3</dvi>
	</div>
</body>
</html>